The flow chart illustrates the stages used to treat river water so that it becomes drinking water. river water $\rightarrow$ settling tank $\rightarrow$ stage $X$ $\rightarrow$ stage $Y$ $\rightarrow$ drinking water What happens at stages $X$ and $Y$?
- A$X$: distillation, $Y$: chlorination
- B$X$: distillation, $Y$: filtration
- C$X$: filtration, $Y$: chlorination
- D$X$: filtration, $Y$: distillation